Ramsey Electronics DDF1 Manual

Doppler direction finder radio direction finder kit

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DOPPLER DIRECTION

RADIO DIRECTION FINDER

Ramsey Electronics Model No.

Get in on the fun of radio direction finding (RDF) with this super

kit ! The latest in affordable Doppler direction finding equipment

available in a complete kit form ..this one even includes the

receiving antenna. A must for the "fox hunter" at an unheard of

price!

•

Elegant and cost effective design thanks to WA2EBY ! Featured in

May / June 1999 QST Articles.

•

Solid state antenna switching for "rock solid" performance.

•

Convenient LED 22.5 degree bearing indicator.

•

Audio Level indicator for trouble free operation.

•

Adjustable damping rate, phase inversion, scan enable / disable.

•

Complete with home brew "mag mount" antennas and cable,

designed for quick set up and operation.

•

Utilizes latest high speed CMOS technology for signal conditioning

and audio processing!

•

Complete and informative instructions guide you to a kit that works

the first time, every time - enhances resale value, too !

FINDER

KIT

DDF1

Table of Contents

Summary of Contents for Ramsey Electronics DDF1

Page 1 DOPPLER DIRECTION FINDER RADIO DIRECTION FINDER Ramsey Electronics Model No. DDF1 Get in on the fun of radio direction finding (RDF) with this super kit ! The latest in affordable Doppler direction finding equipment available in a complete kit form ..this one even includes the receiving antenna.
Page 2 1998 by Ramsey Electronics, Inc. 590 Fishers Station Drive, Victor, New York 14564. All rights reserved. No portion of this publication may be copied or duplicated without the written permission of Ramsey Electronics, Inc. Printed in the United States of America. DDF1 • 2...
Page 3: Table Of Contents
Price $5.00 INSTRUCTION MANUAL FOR DOPPLER RADIO DIRECTION FINDER TABLE OF CONTENTS Introduction to the DDF1 ....4 DDF1 Circuit Description ....4 Parts List ........11 DDF1 Assembly Steps ....14 Component Layout ....... 17 Schematic Diagram ...... 18 Initial Testing ........
Page 4: Ddf1 Circuit Description
DDF1 CIRCUIT DESCRIPTION The classic example of the Doppler effect is that of a car approaching a sta- tionary observer. The car's horn sounds higher in pitch (frequency) to an ob- server as the car approaches.
Page 5 Doppler shift of 500 Hz at 146 MHz, assuming the antenna is turn- ing in a circle with radius 13.39 inches. R F S ig na l (fo ) F ig ure 1 R o ta tio n (A ) (B ) DDF1 • 5...
Page 6 Doppler tone from voice, PL tones and noise. The DDF1 design offers slightly improved audio filtering, 74HC-series logic circuits capable of driving the LED display directly, a wideband VHF/UHF an- tenna switcher and the four 1/4- mag-mount antennas.
Page 7: Circuit Description
+/-250 Hz of that frequency for reasons that I'll discuss shortly. The 8 kHz output of U4 provides the clock for 4 bit binary counter U7. The 3 bit binary coded decimal (BCD) output of U7 is used to operate three synchronized functions. DDF1 • 7...
Page 8 4 kHz/8 =500 Hz. This is the exact frequency at which the antenna spins, hence, the same frequency of the Doppler tone produced on the receiver audio connected to the spinning antenna. This is DDF1 • 8...
Page 9 Doppler tone amplitude drops below 0.11 V peak. This is done by referencing the negative input of U2D to 2.39 V, 0.11 V be- low the nominal 2.5 VDC reference level output of U2B by means of voltage DDF1 • 9...
Page 10: Power Supply
2.5 V above circuit ground allows op amps to process analog signals without the need of a negative power supply voltage. Analog voltages swing from near 0 V to near +5 V with the virtual ground level right in the middle, 2.5 V. DDF1 • 10...
Page 11: Parts List
PC mount 10K trimmer potentiometer (103) [R50] PC mount 500K trimmer potentiometer (504) [R19,36] CAPACITORS AND INDUCTORS 11 1000 pF disc capacitors (labeled .001 or 102) [DDF1 board C22,24,26][ANTINT-1 board C1,2,3,4,5,6,7,8] 4700 pF disc capacitor (labeled .0047 or 472) [C23] 10 .01uF disc capacitors (labeled .01 or 103 or 10nF)
Page 12 SEMICONDUCTORS AND INTEGRATED CIRCUITS 11 1N4148 small signal diode (small glass case with banded end) [DDF1 board D1,2,5 ANTINT-1 board D1,2,3,4 ANTMTG-1 board 1 ea.] IN4000 type power diode (black epoxy package with cathode band) [typically 4001 to 4007] [D6]...
Page 13 RAMSEY Learn-As-You-Build KIT ASSEMBLY There are numerous solder connections on the DDF1 printed circuit board. Therefore, PLEASE take us seriously when we say that good soldering is es- sential to the proper operation of your direction finder! • Use a 25-watt soldering pencil with a clean, sharp tip.
Page 14: Component Layout
DDF1 DOPPLER DIRECTION FINDER ASSEMBLY STEPS Although we know that you are anxious to complete the assembly of your di- rection finder finder kit, it will become necessary to assemble in a specific or- der to accomplish the final components installation of your unit. Try to avoid the urge to “jump ahead”...
Page 15 15. Install C31, .1uF disc capacitor (marked 104). 16. Install R42, 47 ohm (yellow-violet-black). 17. Install C30, 100 uF electrolytic. Be sure to orient the polarity as shown in the diagram. 18. Identify D6, the 1N4002 diode (epoxy case with a polarity “band” de- DDF1 • 15...
Page 16 28. Install U5, the 74HC4051 IC. Make sure not to “bridge” solder be- tween the pins. 29. Install U8, the 74HC42 IC. Solder all 16 pins. 30. Install U12, the 74HC14 inverter IC. 31. Install U7, 74HC161 IC. Watch that orientation! DDF1 • 16...
Page 17 DDF-1 MAIN BOARD PARTS LAYOUT DIAGRAM DDF1 • 17...
Page 18 DDF1 • 18...
Page 19 DDF1 • 19...
Page 20 PC board, facing R24. Mount it as close to the board as possible without forcing it. Carefully solder all three leads. 46. Identify and install C33, a 10 uF electrolytic capacitor. Remember DDF1 • 20...
Page 21 59. Install C7, .1uF disc (marked 104). 60. Install C6, .01 disc capacitor (marked .01 or 103 or 10nF). 61. Install R6, 33K ohm (orange-orange-orange). 62. Install R14, 3.3K ohm (orange-orange-red). 63. Install R13, 10K ohm (brown-black-orange). DDF1 • 21...
Page 22 80. Install C18 and 19, both .01uF (marked .01 or 103 or 10nF). 81. Install R30, 33K ohm (orange-orange-orange). 82. Moving to the right, install R51, 47 ohm (yellow-violet-black). 83 for the final component on the main board component side, install C38 (.01uF) (marked .01 or 103 or 10nF). DDF1 • 22...
Page 23 87. Observe the miniature LED’s provided with your kit. Being diodes, these compo- Leave these leads as long as possible nents are polarized and must be oriented correctly. Examine PC Board one of the LED’s and notice DDF1 • 23...
Page 24 Diode Mounting Diagram 1. Form and install diodes D1, Solder Connection 2, 3, 4 into their respective po- Circuit Trace sitions on the circuit board. PC Board DDF1 • 24...
Page 25 To begin our preparation, locate the length of mini coax included with your kit. Tinned Braid RG-174 Coax 1. Cut four 13 inch pieces Center Conductor of cable to connect the switcher to each antenna assembly. Center Insulation DDF1 • 25...
Page 26 N u t w ith w a s h e r o n to p P la s tic C a p P e e l a n d s tic k m a g n e t DDF1 • 26...
Page 27 Before connecting the antenna switcher, verify the operation of clock oscillator U4 by connecting an oscilloscope to pin 3. The output should be a square wave with an amplitude of 5 V and a period of 125 DDF1 • 27...
Page 28 LED D3 illuminates. Then, adjust R50 until low signal level LED D4 lights. Adjust R50 so that LEDs D3 and D4 are off, set calibrate control R36 to the center of its range and adjust damping control R19 for minimum damp- ing (fully CCW). DDF1 • 28...
Page 29 Doppler RDF unit to operate correctly. A single antenna turned on out of sequence is enough to produce a bogus RDF reading. It does not matter if the antenna spins clockwise or counterclockwise. DDF1 • 29...
Page 30 If you intend to use the DDF1 at highway speeds, you may want to get some stronger magnets. The powerful magnets contained in computer hard drives are excellent for this application and can often be found at flea markets or surplus store for as little as $1.00 or less.
Page 31 It is best to use a smaller, handheld walkie talkie with your DDF1. The unit connects easily to the antenna on your handheld and be- cause they have less output power, there is less chance of doing damage by accidentally transmitting into your DDF1.
Page 32 Insert the two screws into the holes in the case bottom and then place the speaker mounting holes through the screws. A nut on each screw will hold the speaker tight to the case bottom. Plug the DDF1 • 32...
Page 33 Please submit comments or ideas to: Ramsey Electronics Inc. Attn. Hobby Kit Department 793 Canning Parkway Victor, NY 14564 And once again, thanks from the folks at Ramsey! DDF1 • 33...
Page 34: Schematic Diagram
DDF-1 ANTENNA SCHEMATIC DIAGRAM DDF1 • 34...
Page 35 '1K ohm' resistors are actually the 'missing' 10 K parts ("Hum-m-m, I guess the 'red' band really does look orange!") Ramsey Electronics project kits are packed with pride in the USA. If you believe we packed an incorrect part or omitted a part clearly indicated in your assembly manual as supplied with the basic kit by Ramsey, please write or call us with information on the part you need and proof of kit purchase.
Page 36: Initial Testing
Doppler Radio Direction Finder Quick Reference Page Guide Introduction to the DDF1 ....4 DDF1 Circuit Description ....4 Parts List ........11 DDF1 Assembly Steps ....14 Component Layout .......17 Schematic Diagram ......18 Initial Testing .........22 Ramsey Warranty ......23 REQUIRED TOOLS •...